package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

// TestAuditDailyRotation 验证跨日 lazy rotation
// 模拟 4 天的写入, 期望产出 4 个不同日期的文件
func TestAuditDailyRotation(t *testing.T) {
	tmp := t.TempDir()

	// 临时改全局 auditDir, 函数返回后恢复
	oldDir := *auditDir
	*auditDir = tmp
	defer func() {
		*auditDir = oldDir
		// 关闭可能打开的文件
		if auditFile != nil {
			auditFile.Close()
			auditFile = nil
		}
		auditCurDay = ""
	}()

	// 模拟连续 4 天的写入
	base := time.Date(2026, 6, 20, 10, 0, 0, 0, time.UTC)
	for i := range 4 {
		day := base.Add(time.Duration(i) * 24 * time.Hour)
		auditMu.Lock()
		if err := openAuditFor(day); err != nil {
			t.Fatalf("day %d: openAuditFor: %v", i, err)
		}
		if _, err := auditFile.Write([]byte("event on " + day.Format("2006-01-02") + "\n")); err != nil {
			t.Fatalf("day %d: write: %v", i, err)
		}
		auditMu.Unlock()
	}

	// 验证: 4 个文件, 每个含 1 条事件
	entries, err := os.ReadDir(tmp)
	if err != nil {
		t.Fatal(err)
	}
	if len(entries) != 4 {
		t.Fatalf("expected 4 files, got %d: %v", len(entries), entries)
	}
	for _, e := range entries {
		name := e.Name()
		if !strings.HasSuffix(name, ".log") {
			t.Errorf("unexpected file: %s", name)
		}
		body, _ := os.ReadFile(filepath.Join(tmp, name))
		expected := "event on " + strings.TrimSuffix(name, ".log")
		if string(body) != expected+"\n" {
			t.Errorf("%s: got %q, want %q", name, body, expected+"\n")
		}
	}
}

// TestAuditNoRotateSameDay 验证同一天多次调用不会关闭/重开文件
func TestAuditNoRotateSameDay(t *testing.T) {
	tmp := t.TempDir()
	oldDir := *auditDir
	*auditDir = tmp
	defer func() {
		*auditDir = oldDir
		if auditFile != nil {
			auditFile.Close()
			auditFile = nil
		}
		auditCurDay = ""
	}()

	day := time.Date(2026, 6, 23, 14, 30, 0, 0, time.UTC)

	auditMu.Lock()
	if err := openAuditFor(day); err != nil {
		t.Fatal(err)
	}
	f1 := auditFile
	if err := openAuditFor(day.Add(1 * time.Hour)); err != nil {
		t.Fatal(err)
	}
	f2 := auditFile
	auditMu.Unlock()

	if f1 != f2 {
		t.Error("expected same file handle for same day")
	}
}

// TestAuditRotateClosesOld 验证跨日时旧文件被 close
func TestAuditRotateClosesOld(t *testing.T) {
	tmp := t.TempDir()
	oldDir := *auditDir
	*auditDir = tmp
	defer func() {
		*auditDir = oldDir
		if auditFile != nil {
			auditFile.Close()
			auditFile = nil
		}
		auditCurDay = ""
	}()

	day1 := time.Date(2026, 6, 23, 23, 59, 0, 0, time.UTC)
	day2 := day1.Add(2 * time.Minute) // 跨过午夜

	auditMu.Lock()
	if err := openAuditFor(day1); err != nil {
		t.Fatal(err)
	}
	oldFile := auditFile
	if err := openAuditFor(day2); err != nil {
		t.Fatal(err)
	}
	newFile := auditFile
	auditMu.Unlock()

	if oldFile == newFile {
		t.Error("expected different file handles after rotation")
	}
	// 旧文件应已被 close
	if _, err := oldFile.WriteString("test"); err == nil {
		t.Error("old file should be closed")
	}
}